An orphan drug is a medication developed to treat rare diseases or conditions that affect a small number of patients. These diseases, often referred to as orphan diseases, may not attract significant investment from pharmaceutical companies due to the limited market size. As a result, governments and regulatory agencies provide incentives to encourage the development of these drugs. To qualify as an orphan drug, a treatment must meet specific criteria, such as affecting fewer than 200,000 people in the United States. The Orphan Drug Act of 1983 in the U.S. was established to promote research and development of these medications, offering benefits like tax credits and extended market exclusivity.